Numerous personal computers are connected to other computer systems or to computer networks such as the Internet through the public switched telephone network (PSTN). A common way of connecting a computer to the PSTN for communication with other computers or computer networks is through the use of a modem. Most modems are capable of operating at different transmission rates at different times, and have a typical maximum communication rate of 56 kbps.
Generally, both the transmitting modem and the receiving modem must evaluate the communication channel first in order to optimize the performance. One way of achieving this is, during “handshaking,” to have the transmitting modem transmit, as part of its set-up sequence to the receiving modem, a composite signal which will be recognized by the receiving modem. This allows the receiving modem to evaluate the communication channel and condition itself to have an optimized data rate for this connection. Modems operating under the V.34 and V.90 standards perform such line probing to maximize the data communication rate.
The maximum communication rate that a modem can achieve is related to the hardware or circuit characteristics associated with a particular customer subscriber loop. The subscriber loop is the twisted copper pairs of wires running to a home or a business from the telephone Central Office switching system. The physical characteristics of a particular subscriber loop may effectively limit the transmission rate for a particular customer. There are numerous other problems, however, unrelated to the physical characteristics of the customer subscriber loop, which can degrade communication performance resulting in lower modem transmission rates. Therefore, for customers experiencing degraded modem performance, there is a need for determining whether the characteristics of the customer subscriber loop is responsible for the degraded modem performance.
Presently, a telephone company technician must be dispatched to the particular customer location with special testing equipment to determine the characteristics of the customer subscriber loop. Troubleshooting customer modem transmission problems by dispatching technicians is expensive and time consuming. Accordingly, what is needed is an inexpensive and remotely located system and method for testing subscriber loop characteristics for a particular customer.